Palestinian protesters run during clashes with Israeli troops at Israel-Gaza border, in the southern Gaza Strip April 5, 2018.
Journalists reported being targeted by both live fire and tear gas up to 500 meters from the Gaza-Israel border fence.
Military officials say they have used live fire only as a last resort when all other alternatives, including warning shots and rubber bullets, have failed to stop the demonstrators from reaching the fence. In a statement on Thursday, UN Special Coordinator Nikolay Mladenov said he is "following with concern" the continuing preparations and rhetoric for Friday's so-called "Great Return March" in Gaza.
"The IDF (Israeli Defence Forces) uses means such as warnings, riot dispersal means, and as a last resort firing live rounds in a precise, measured way", it said Saturday.
According to the statistics, about 70 percent of Gaza's two million residents are refugees or the descendants of those displaced from towns and villages now in Israel.
The Israeli military accused the "approximately 10,000 Palestinians" who attended of "rioting in five locations along the border with the Gaza Strip".
At least 17 protesters were killed and more than 1,400 were injured when the protests in Gaza on March 30 took a violent turn.
The Israeli military says Hamas has been using the demonstrations as cover for attacks, and says militants have attempted to carry out shootings, plant bombs and infiltrate the fence in order to attack inside Israel.
Numbers were down from the previous Friday, when tens of thousands approached the border in demonstrations that saw Israeli forces kill 19 Palestinians, making it the bloodiest day in Gaza since a 2014 war. And yet, only Palestinians reportedly suffered injuries and deaths.
"Firing live ammunition into crowds of unarmed civilians is illegal and inhumane and can not be tolerated".
The European Union on Saturday issued a statement saying Friday's violence "raises serious questions about the proportionate use of force which must be addressed". Of the 21 dead so far, 15 were killed during border protests, and videos and witness accounts indicate that most were not armed or carrying out attacks at the moment they were killed. "He just fell on the ground and said, "I've been shot, I've been shot".
"We have no interest in harming women and children who are protesting".